Setup SSH Passwordless Login in OpenSSH

You can login to a remote Linux server without entering password using ssky-keygen and ssh-copy-id as explained in this example.

ssh-keygen creates the public and private keys. ssh-copy-id copies the local-host’s public key to the remote-host’s authorized_keys file. sshcopy-id also assigns proper permission to the remote-host’s home, ~/.ssh, and ~/.ssh/authorized_keys.

Step 1: Create public and private keys using ssh-key-gen on local-host

sathish@local-host$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key

(/home/sathish/.ssh/id_rsa):[Enter key]

Enter passphrase (empty for no passphrase): [Press enter key]

Enter same passphrase again: [Pess enter key]

Your identification has been saved in

/home/sathish/.ssh/id_rsa.

Your public key has been saved in

/home/sathish/.ssh/id_rsa.pub.

The key fingerprint is:

33:b3:fe:af:95:95:18:11:31:d5:de:96:2f:f2:35:f9

Step 2: Copy the public key to remote-host using sshcopy-id

sathish@local-host$ ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host

sathish@remote-host’s password:

Now try logging into the machine, with “ssh ‘remotehost’”,and check in:

.ssh/authorized_keys to make sure we haven’t added extra keys that you weren’t expecting.